The present invention pertains generally to drainage devices for use in the removal of fluids, such as liquids and gases, from body cavities of medical patients. More particularly, the invention relates to suction drainage systems which incorporate an improved suction control chamber for governing the flow pattern of air and liquid within the chamber. The present invention also includes a valve for maintaining desired pressure levels in a collection chamber of a drainage device. Furthermore, the invention includes a tube coupling device having a sample collection or injection port.
There have been a number of patient drainage devices introduced into the marketplace over the years. Typically, a drainage system incorporating a water filled manometer in the suction control chamber is connected to a central vacuum supply line in a hospital to provide a source of suction pressure. The suction permits withdrawal of fluids, such as blood, water and gas, from a patient's pleural cavity by establishing a pressure differential between the suction source and the internal pressure in the patient. Suction pressure and pressure differentials must be controlled to avoid harm to the patient should unduly high or low pressure differentials occur. However, since the hospital suction source is not typically constant, the degree of suction imposed on the drainage device varies. Therefore, there exists a need for regulating the degree of vacuum maintained in the collection chamber of the drainage device.
A number of wet suction control drainage devices have been introduced to regulate the pressure in the collection chamber through use of a water filled manometer in the suction control chamber. Devices of this type can be found, for example, in U.S. Pat. Nos. 3,559,647; 3,683,913; 4,439,190; and 4,465,483, to mention but a few. Despite the general acceptance of wet suction control drainage devices in the medical community, there remains a continuing need to improve the convenience and performance of chest drainage systems and to render such systems compact.
Typically, wet suction control drainage devices incorporating a water filled manometer, in use, draw gas, typically air, into and up through the water in the large arm of the manometer. The gas drawn into the system causes turbulence in the water and raises the water level. If the source of suction is sufficiently high, turbulence is increased and water can be lifted and spilled over into the next chamber of the device. Also, a high degree of turbulence could increase the rate of evaporation of water from the suction control chamber. Either situation would require water replacement if predetermined pressure levels are to be maintained. To control spillover and evaporation, some devices have employed flow directional guides in the large arm portion of the manometer. The guides, in effect, direct the gas and water by imparting a rotational or swirling motion to the gas and water body. However, such a body motion can drive the gas into the water instead of directing the gas up and out of the chamber. This condition might result in increased dispersion and entrainment of gas in the water, increased water lift, and increased rate of water evaporation.
We have invented an improved drainage device which provides additional improvements to presently available devices. The levels of suction obtained by a water controlled chest drainage system are somewhat limited by the size of the monometer tube required to maintain such suction levels. For high levels of suction, the size of manometer required would in some circumstances render the drainage system impractical. An obvious approach to solving the water spillover problem would be to increase the overall height of the drainage unit. Here we have reduced the unit height rendering the unit more compact. Another approach, aimed at reducing the effect of evaporation, would be to increase water volume. Here we have maintained the water volume at a convenient level of 500 cubic centimeters and reduced the evaporation rate. We have achieved these results by improving the gas flow pattern through the suction control chamber which reduces turbulence in the chamber. The resulting major improvements are reduction in water evaporation rate, virtual elimination of water spillover from the suction control chamber, lower noise levels, and higher gas flow capabilities.
In the chamber of the drainage device used to collect fluids drained from the plural cavity, it is possible to develop below normal pressure levels. These below normal pressure levels could result from a patient vigorously coughing, from forced inspiration caused by an upper airway obstruction, and from the stripping of the drainage tube. In the event of below normal pressure levels, it is desirable to restore the pressure to a normal level. Accordingly, we have developed a unique negativity relief valve to restore normal pressure. Although there have been a number of different approaches followed to achieve this goal, the valve we have developed requires fewer parts and fewer process manufacturing steps.
During the drainage procedure, it is at times advantageous or desirable to draw a fresh sample of fluid drainage from the patient for testing procedures. Also, it might be advantageous to inject fluids, such as anticoagulant or medication into the drawn fluid before return of the fluid to the patient during a reinfusion procedure. According to currently available methods for obtaining drainage samples, some chest drainage devices include a resealable site in the collection chamber. However, with this method one cannot obtain a fresh sample unless the sample is withdrawn during the initial drainage procedure since the collection chamber invariably would contain fluids that have collected over a period of time. Nor does such a resealable site allow for the infusion of any drugs into the patient. Another common method is to sample directly through the patient tubing which is typically formed of latex. Although manufacturers of latex tubing claim that the latex tubing is self-sealing, tests have indicated that leakage occurs under normal operating conditions. Another disadvantage with such a sampling/injection method is the possibility that the needle of a hypodermic needle may pass through both walls of the tubing and possibly stick and injure a clinican's skin. The risk of blood contact by the clinician would therefore exist everytime a sample is withdrawn or injected into the latex tubing. Accordingly, we have invented a tube coupling apparatus which permits both fresh sample withdrawal and medication injection at a common site using a hypodermic needle without the danger of tube damage and the associated risks.